A collision detection device for a vehicle is configured to detect a frontal collision or a side collision of a vehicle and to determine whether an occupant protection device should be activated. The occupant protection device includes, for example, an airbag, a seatbelt pretensioner and the like. The vehicle is configured to activate the occupant protection device based on the determination of the collision by the collision detection device so as to protect an occupant from impact of the collision. As an example of such a collision detection device for a vehicle, according to JP-A-2004-148864, multiple acceleration sensors are disposed and impact of a collision is detected as acceleration, and then, whether an occupant protection device is activated is determined. According to JP-A-2006-306155, which corresponds to US 2006/0237255, a pressure sensor is disposed in a door interior space of a vehicle and a pressure change in the door interior space in a collision is detected. In such a configuration, a side collision of the vehicle can be detected by the pressure sensor.
A collision detection device for a vehicle detects a collision with the vehicle by a pressure sensor or the like, and determines whether an occupant protection device should be activated with respect to the collision. In order to respond to various types of the vehicle collisions and to improve reliability of the occupant protection in the collision, the collision detection device needs to perform the determination promptly.